The present invention relates to an optical disc apparatus for conducting recording/reproducing of information onto/from an optical recording medium, such as, an optical disc, representatively, for example, and in particular, it relates to an optical disc apparatus for conducting recording/reproducing of information onto/from an optical disc having a plural number of recording layers thereon.
In general, within the optical disc apparatus, a coma aberration generates on an optical spot of condensed lights, because of an inclination (i.e., a tilt) of the disc with respect to an optical axis of a laser beam, which is generated due to warping or curving of the disc and/or a clamping error, etc.
Also, as a document relating to a tilt control or adjustment of, there is already known the following Patent Document 1. The invention described in the Patent Document 1 relates to a tilt correction processing method in an optical disc apparatus, which can record or reproduce information by irradiating a laser beam onto respective layers of the optical having plural numbers of recording/reproducing layers thereon. Also, in the Patent Document 1, there is the following description, for example, in the claim 1 thereof; “A tilt correction processing method for correcting a tilt amount or volume, being an inclination of a recording/reproducing surface of the optical disc with respect to an optical axis of the laser beam, comprising the following steps of: setting up the tilt volume in a step-like manner within a predetermined region, at a predetermined radial position on a recording/reproducing surface locating at the farthest distance from an irradiation side of said laser beam, within said plural numbers of layers; obtaining an optimal tilt correction volume upon basis of a calculation value of a predetermined signal, which can be obtained from said optical disc with respect to the tilt correction volume set up; and applying said optimal correction volume obtained also on a recording/reproducing layer other than said recording/reproducing layer locating at the farthest distance from the irradiation side of said laser beam”.
Further, as a document relating to the tilt adjustment, there is also the following Patent Document 2. In this Patent Document 2, there is the following description, for example, in the claim 7 thereof; “The optical disc apparatus, wherein said serve parameter setup means adjusts a tilt mechanism for each of regions divided on one (1) recording surface, and memorized an adjustment value of brining amplitude of said data reproduction signal to be the maximum into a memorizing means, and an adjustment value for other recording surface is set to a value, which is obtained by adding a predetermined value or multiplying a predetermined value onto an adjustment value of the same region on the recording surface, which is already adjusted”.
<Prior Art Documents>
<Patent Documents>
[Patent Document 1] Japanese Patent No. 4069087; and
[Patent Document 2] Japanese Patent Laying-Open No. 2008-090911 (2008).